ARCA MK Series User manual

MK
PRK
Installation
Usage
Maintenance

i
TABLE OF CONTENTS
1. IMPORTANT .......................................................................................................................................................1
2. TECHNICAL DATA.............................................................................................................................................2
2.1 MAIN SPECIFICATIONS OF MK BOILERS..................................................................................................2
2.2 MK BOILER DIMENSIONS............................................................................................................................4
2.3 TECHNICAL SPECIFICATIONS OF PRK BOILERS ....................................................................................5
2.4 DIMENSIONS OF PRK BOILERS .................................................................................................................8
3. SWITCHBOARD .................................................................................................................................................9
3.1 SWITCHBOARD ............................................................................................................................................9
3.2 WIRING DIAGRAM........................................................................................................................................9
3.3 TERMINAL BOX CONNECTIONS ..............................................................................................................10
3.4 WATER STORAGE CYLINDER CONNECTIONS ......................................................................................10
3.5 RUNNING ....................................................................................................................................................10
4. BURNERS .........................................................................................................................................................11
4.1 MINIMAL VALUE OF THE BURNER OUTPUT AT FIRST STAGE ............................................................12
5. INSTALLATION ................................................................................................................................................12
5.1 HYDRAULIC DIAGRAM ..............................................................................................................................12
5.2 JACKET MOUNTING...................................................................................................................................13
5.3 ANTICONDENSATION PUMP ....................................................................................................................15
5.4 FLUE ............................................................................................................................................................15
6. USAGE ..............................................................................................................................................................15
6.1 FIRST IGNITION CONTROL.......................................................................................................................15
6.2 RUNNING DATA..........................................................................................................................................15
6.3 REDUCED OUTPUT RUNNING .................................................................................................................16
6.4 BOILER WATER TEMPERATURE .............................................................................................................16
6.5 SYSTEM IGNITION .....................................................................................................................................16
6.6 BOILER THERMOSTAT SET VALUES.......................................................................................................16
6.7 BOILER WATER..........................................................................................................................................17
7. MAINTENANCE ................................................................................................................................................18
7.1 EVERYDAY MAINTENANCE OPERATIONS .............................................................................................18
7.2 SEASONAL MAINTENANCE OPERATIONS..............................................................................................18
7.3 DOOR TIGHTNESS CONTROL..................................................................................................................19
7.4 BOILER SCALING .......................................................................................................................................19
7.5 PERIODIC CONTROLS...............................................................................................................................19
8. CERTIFICATIONS ............................................................................................................................................20

1
1. IMPORTANT
This book is an important part of the product and it should be given to the user.
Read carefully all information about installation safety, usage and maintenance. Keep the handbook carefully.
Professional qualified people in according to common law following the producer’s instructions should carry out
the installation. A wrong installation could cause damage to persons, things and animals for which the producer
is not responsible.
Control the product integrity. If you have any doubt do not use the device and call your supplier. The packaging
has not to be left in the environment. Do not let children play with it.
Before doing every kind of maintenance or cleaning operation, disconnect the boiler from its electric supply
working on the installation switch.
In case of boiler damage or malfunctioning, make inactive the boiler and do not try to repair it. Call the post-sale
authorised centre. Use only original spare parts.
The non – observance of the above mentioned notices could seriously compromise the boiler safety.
This boiler has to be used only according to the usage it was planned for. Every kind of other usage has to be
considered improper and dangerous. The producer is not to be considered responsible for possible damages
caused by wrong, improper and unreasonable usage.
Every kind of producer's responsibility for damages caused by installation and usage errors is excluded.

2
2. TECHNICAL DATA
2.1 MAIN SPECIFICATIONS OF MK BOILERS
− Pressurized steel boiler, for heating systems with hot water production up to 95°C.
− Output: from 44 to 269 kW. - Running: light oil-gas.
− Cylindrical furnace, flame inversion, detached from the back duct plate, arc-welded on a copper bar.
− Steel boiler body Fe360 UNI EN 10025/92, completely electro-welded in a CO2 controlled atmosphere.
− Steel duct bundle Fe360D UNI EN 10204/2.2, 4 mm thickness.
− Completely adjustable door allowing perfect combustion product tightness.
− Epoxy enamelled boiler jacket, 80 mm thick glass fibre insulation pad to reduce passive heat leakages.
− The switchboard is outside the jacket and is fitted with an operating thermostat, a manual reset safety thermostat, a thermometer, a
minimal temperature thermostat on the circulating pump, an anti-inertia thermostat, a general switch, a circulating pump switch and
burner switch. Rubber sheath with IP 40 minimal protection level.
MK 55 MK 70 MK 80 MK 90 MK 100
kW
kcal/h
44 ÷ 54,7
37.840 ÷ 47.042
50 ÷ 68,4
43.000 ÷ 58.824
62 ÷ 80,1
53.320 ÷ 68.846
75 ÷ 90,3
64.500 ÷ 77.658
90 ÷ 100,1
77.400 ÷ 86.086
kW
kcal/h
48 ÷ 60,2
41.280 ÷ 51.772
54 ÷ 74,7
46.440 ÷ 64.242
67 ÷ 87,4
57.620 ÷ 75.164
80,5 ÷ 98,8
69.230 ÷ 84.968
97 ÷ 109,3
83.420 ÷ 93.998
Combustion chamber volume m³ 0,056 0,056 0,056 0,100 0,100
kW/m³
kcal/h m3
1.075
924.500
1.334
1.147.179
1.561
1.342.214
988
849.680
1.093
939.980
Exchange surface m² 2,7 2,7 2,7 4,3 4,3
kW/m²
kcal/h m²
20,3
17.423
25,3
21.787
29,7
25.513
21,0
18.060
23,3
20.020
Smoke duct number n° 18 18 18 23 23
Smoke duct diameter Ø est. 1½” 1½” 1½” 1½” 1½”
Boiler weight kg 200 220 220 300 310
Water content l 90 90 90 140 140
Operating pressure bar 5 5 5 5 5
Hydraulic pressure bar 7,5 7,5 7,5 7,5 7,5
Max. operating temperature °C 95 95 95 95 95
Water loss of heat ∆t=15°C mbar
8 10 13 12 14
Combustion chamber pressure mbar 0,12 0,15 0,2 0,24 0,36
Min. efficiency at 100% % 87,5 87,7 87,8 87,9 88
Efficiency at 100% % 90,7 91,5 91,5 91,3 91,5
Min. efficiency at 30% % 85,3 85,5 85,8 85,9 86,1
Efficiency at 30% % 88,5 88,9 89 89,3 90,1
Loss of heat at the chimney with operating burner % 8,2 7,48 7,45 7,61 7,35
Loss of heat at the chimney with burner out % 0,28 0,3 0,26 0,32 0,26
Jacket losses ∆t=50°C %
1,1 1,02 1,05 1,09 1,15
Burner connection (Ø) mm 125 125 125 150 150
Flue connection (Ø) mm 200 200 200 200 200
Min. chimney depression mbar 0,2 0,2 0,2 0,2 0,2
Max. smoke temperature °C 180 185 188 181 185
Smoke temperature in output range °C 141 ÷ 180 148 ÷ 185 151 ÷ 188 146 ÷ 181 155 ÷ 185
CO2a gas % 9,8 9,7 10 9,6 9,75
CO a gas ppm 27 24 22 25 19
NOx a gas ppm 43 39 42 45 40
Max. light oil smoke flow rate m³/h 150 180 210 240 270
Max. methane smoke flow rate m³/h 133 159 185 212 239
Light oil burning air volume (practice) m³/h 82 98 114 131 148
Methane burning air volume (practice) m³/h 76 90 105 120 136
Combustion chamber dimension (DiameterXLenght) mm 330 ×650 330 ×650 330 ×650 390 ×830 390 ×830
Thermostat adjustment range °C 55 ÷ 80 55 ÷ 80 55 ÷ 80 55 ÷ 80 55 ÷ 80
Output
Fornace output
Thermal load
Thermal output

3
MK 120 MK 140 MK 170 MK 230 MK 300
kW
kcal/h
102 ÷ 120,2
87.720 ÷ 103.372
120 ÷ 140,3
103.200 ÷ 120.658
145 ÷ 170,1
124.700 ÷ 146.286
174 ÷ 230
149.640 ÷ 197.800
220 ÷ 291,7
189.200 ÷ 250.862
kW
kcal/h
110 ÷ 131,1
94.600 ÷ 112.746
130 ÷ 153,3
111.800 ÷ 131.838
157 ÷ 186,1
135.020 ÷ 160.046
188 ÷ 250,5
161.680 ÷ 215.430
237 ÷ 319,7
203.820 ÷ 274.942
Combustion chamber volume m³ 0,100 0,121 0,121 0,190 0,235
kW/m³
kcal/h m3
1.311
1.127.460
1.267
1.089.570
1.538
1.322.694
1.318
1.133.842
1.360
1.169.966
Exchange surface m² 4,3 5,1 5,1 6,5 7,9
kW/m²
kcal/h m²
28,0
24.040
27,5
23.658
33,4
28.684
35,4
30.431
36,9
31.755
Smoke duct number n° 23 23 23 28 28
Smoke duct diameter Ø est. 1½” 1½” 1½” 1½” 1½”
Boiler weight kg 310 340 340 410 460
Water content lt. 140 180 180 280 300
Operating pressure bar 5 5 5 5 5
Hydraulic pressure bar 7,5 7,5 7,5 7,5 7,5
Max. operating temperature °C 95 95 95 95 95
Water loss of heat ∆t=15°C mbar
18 20 22 25 30
Combustion chamber pressure mbar 0,5 0,7 1,2 1,5 3,2
Min. efficiency at 100% % 88,2 88,3 88,5 88,7 88,8
Efficiency at 100% % 91,6 91,3 91,3 91,8 91,0
Min. efficiency at 30% % 86,3 86,5 86,8 87,1 87,2
Efficiency at 30% % 92,8 92,5 92,6 93 92,0
Loss of heat at the chimney with operating burner % 7,27 7,66 7,58 7,18 7,84
Loss of heat at the chimney with burner out % 0,25 0,29 0,22 0,24 0,26
Jacket losses ∆t=50°C %
1,13 1,04 1,12 1,02 0,96
Burner connection (Ø) mm 150 150 150 185 185
Flue connection (Ø) mm 200 200 200 250 250
Min. chimney depression mbar 0,2 0,2 0,2 0,2 0,2
Max. smoke temperature °C 196 186 188 182 198
Smoke temperature in output range °C 169 ÷ 196 145 ÷ 186 150 ÷ 188 142 ÷ 182 149 ÷ 198
CO2a gas % 10,2 10,5 9,9 9,7 10
CO a gas ppm 28 26 22 16 21
NOx a gas ppm 48 42 50 44 49
Max. light oil smoke flow rate m³/h 314 373 453 599 756
Max. methane smoke flow rate m³/h 278 338 411 531 665
Light oil burning air volume (practice) m³/h 171 197 239 327 413
Methane burning air volume (practice) m³/h 158 175 213 302 376
Combustion chamber dimension (DiameterXLenght) mm 390 ×830 390 ×1.010 390 ×1.010 468 ×1.050 468 ×1.300
Thermostat adjustment range °C 55 ÷ 80 55 ÷ 80 55 ÷ 80 55 ÷ 80 55 ÷ 80
Output
Fornace output
Thermal load
Thermal output

4
2.2 MK BOILER DIMENSIONS
1 Switchboard AB Burner connections
3 Sight glass AC Flue connection
AM Flow connection * Only for 220 - 280 models
AR Return connection
Mod. A
mm
B
mm
C
mm
G
mm
H
mm
N
mm
R
mm
S
mm
T
mm
AR-AM
Ø DN
AC
Ø mm
AB
Ø mm
AS
Ø
55 670 790 1020 110 640 310 500 595 710 1½” 200 120 ½”
70 670 790 1020 110 640 310 500 595 710 1½ ” 200 120 ½”
80 670 790 1020 110 640 310 500 595 710 1½ ” 200 120 ½”
90 730 890 1210 110 720 310 580 660 890 2” 200 150 ½”
100 730 890 1210 110 720 310 580 660 890 2” 200 150 ½”
120 730 890 1210 110 720 310 580 660 890 2” 200 150 ½”
140 730 890 1390 110 720 310 580 660 1070 2” 200 150 ½”
170 730 890 1390 110 720 310 580 660 1070 2” 200 150 ½”
230 850 1010 1430 135 / 380 610 780 1110 65 250 185 1”
300 850 1010 1680 135 / 380 610 780 1360 65 250 185 1”

5
2.3 TECHNICAL SPECIFICATIONS OF PRK BOILERS
− Steel boiler with pressurized combustion, for heating and hot water systems up to 95° C.
− Output: from 260 up to 3500 kW.
− Running : light oil and gas.
− Cylindrical furnace with flame inversion, detached from the back duct plate, arc-welded on a copper bar.
− Steel boiler body Fe 360 UNI EN 10025/92, completely electro-welded in a CO2 controlled atmosphere.
− Steel duct bundle Fe 360D UNI EN 10204/2.2, 4 mm thickness.
− Dispenser of the return water returning from the system towards the front duct plate allowing a better cooling and limiting carbonate and
magnesium deposits.
− Completely adjustable door allowing perfect combustion product tightness.
− Epoxy enamelled steel jacket with, and boiler body insulation by means of 80 mm thick glass fibre pad.
− The switchboard is outside the jacket and fitted with a manual reset thermostat, a thermometer, a minimal temperature thermostat, an
anti-inertia thermostat, a general switch, a circulating pump switch and a burner switch. Rubber sheath with IP40 minimal protection
level.
PRK 350 PRK 420 PRK 470 PRK 520 PRK 600
kW
kcal/h x 1000
260 ÷ 349
223,6 ÷ 300,14
300 ÷ 419
258 ÷ 360,34
380 ÷ 470
326,8 ÷ 404,2
400 ÷ 524
344 ÷ 450,64
470 ÷ 600
404,2 ÷ 516
kW
kcal/h x 1000
281 ÷ 379
241,6 ÷ 325,94
324 ÷ 457,8
278,6 ÷ 393,7
410 ÷ 510,5
352,6 ÷ 439,03
430 ÷ 571
369,8 ÷ 491,06
506 ÷ 654
435,1 ÷ 562,4
Combustion chamber volume m³ 0,293 0,293 0,39 0,39 0,467
kW/m³
kcal/h m³
1.293,5
1.112.410
1.562,4
1.343.664
1.308,9
1.125.654
1.464
1.259.040
1.400,4
1.204.344
Exchange surface m² 8,3 9,3 9,7 9,7 12
kW/m²
kcal/h m²
42
36.120
45
38.700
48,5
41.710
54
46.440
50
43.000
Smoke duct number n° 28 30 33 33 33
Smoke duct diameter Ø est. 1½” 1½” 1½” 1½” 1½”
Boiler weight kg 650 740 1.070 1.070 1.250
Water content lt. 340 400 470 470 570
Operating pressure bar 6 6 6 6 6
Hydraulic pressure bar 9 9 9 9 9
Max. operatine temperature °C 95 95 95 95 95
Water loss of heat ∆t=15°C mbar
24 38 19 23 32
Combustion chamber pressure mbar 2,4 3,6 3,8 4,1 4,8
Minimum efficiency at 100% % 89 89,2 89,2 89,2 89,2
Efficiency at 100% % 90,2 91,5 92 91,7 91,7
Minimum effciency at 30% % 87,6 87,8 87,8 87,8 87,8
Efficiency at 30% % 91,3 92,8 93,4 93 93
Loss of heat at the chimney with working burner % 7,38 7,8 7,45 7,65 7,65
Loss of heat at the chimney with burner out % 0,25 0,24 0,2 0,22 0,22
Loss of heat at the jacket ∆t=50°C %
0,62 0,7 0,55 0,65 0,65
Burner connection (Ø) mm 210 210 240 240 240
Flue connection (Ø) mm 250 250 300 300 300
Min. chimney depression mbar 0,2 0,2 0,2 0,2 0,2
Max smoke temperature °C 190 188 180 185 190
Smoke temperature in the output range °C 151 ÷ 190 147 ÷ 188 148 ÷ 180 151 ÷ 185 151 ÷ 190
CO2a gas % 9,8 9,7 10 9,9 9,9
CO a gas ppm 6 15 28 19 19
NOx a gas ppm 56 48 61 52 52
Max. light oil smoke flow rate m³/h 894 1.080 1.205 1.344 1.595
Max. methane smoke flow rate m³/h 790 967 1.064 1.200 1.447
Light oil burning air volume (practice) m³/h 489 590 658 735 842
Methane burning air volume (practice) m³/h 450 544 616 684 749
Combustion chamber dimensions (DiameterxLenght) mm 530 ×1.300 530 ×1.300 628 ×1.250 628 ×1.250 628 ×1.500
Thermostat adjustment range °C 55 ÷ 80 55 ÷ 80 55 ÷ 80 55 ÷ 80 55 ÷ 80
Output
Fornace output
Thermal load
Thermal output

6
PRK 700 PRK 830 PRK 940 PRK 1050 PRK 1200
kW
kcal/h x 1000
539 ÷ 698
463,5 ÷ 600,28
670 ÷ 830
576,2 ÷ 713,8
760 ÷ 940
653,6 ÷ 808,4
820 ÷ 1.050
705,2 ÷ 903
950 ÷ 1.200
817 ÷ 1.032
kW
kcal/h x 1000
586 ÷ 759,5
503,9 ÷ 653,17
724 ÷ 906
622,64 ÷ 779,16
815 ÷ 1.025
700,9 ÷ 881,5
888 ÷ 1.148
763,68 ÷ 987,28
1.029 ÷ 1.315
884,94 ÷ 1.130,9
Combustion chamber volume m³ 0,607 0,676 0,95 0,95 1,056
kW/m³
kcal/h m³
1.251
1.075.860
1.340,2
1.152.572
1.079
927.854
1.208,4
1.039.224
1.245,2
1.070.872
Exchange surface m² 13,7 15,6 19,6 19,6 23
kW/m²
kcal/h m²
50,9
43.774
53,2
45.752
47,9
41.194
53,5
46.010
52,1
44.806
Smoke duct number n° 40 40 49 49 49
Smoke duct diameter Ø est. 1½” 1½” 1½” 1½” 1½”
Boiler weight kg 1.650 1.750 1.850 1.850 2.050
Water content lt. 620 720 1.070 1.070 1.360
Operating pressure bar 6 6 6 6 6
Hydraulic pressure bar 9 9 9 9 9
Max. operatine temperature °C 95 95 95 95 95
Water loss of heat ∆t=15°C mbar
26 30 40 45 54
Combustion chamber pressure mbar 5,7 6,2 5,2 5,6 6,2
Minimum efficiency at 100% % 89,2 89,2 89,2 89,2 89,2
Efficiency at 100% % 91,9 91,5 91,7 91,25 91,3
Minimum effciency at 30% % 87,8 87,8 87,8 87,8 87,8
Efficiency at 30% % 93,9 92,2 93,2 92,9 93,2
Loss of heat at the chimney with working burner % 7,65 8 7,78 8,17 8,22
Loss of heat at the chimney with burner out % 0,18 0,21 0,18 0,20 0,18
Loss of heat at the jacket ∆t=50°C %
0,45 0,5 0,52 0,58 0,48
Burner connection (Ø) mm 240 240 305 305 305
Flue connection (Ø) mm 350 350 400 400 400
Min. chimney depression mbar 0,2 0,2 0,2 0,2 0,2
Max smoke temperature °C 192 185 181 189 192
Smoke temperature in the output range °C 142 ÷ 192 147 ÷ 185 144 ÷ 181 149 ÷ 189 153 ÷ 192
CO2a gas % 10,3 10,2 10,3 9,8 10,3
CO a gas ppm 58 69 49 55 49
NOx a gas ppm 67 71 54 52 54
Max. light oil smoke flow rate m³/h 1.810 2.210 2.436 2.801 3.209
Max. methane smoke flow rate m³/h 1.631 2.004 2.140 2.540 2.909
Light oil burning air volume (practice) m³/h 979 1.166 1.331 1.478 1.693
Methane burning air volume (practice) m³/h 902 1.038 1.220 1.316 1.507
Combustion chamber dimensions (DiameterxLenght) mm 718 ×1500 718 ×1670 820 ×1750 820 ×1750 820 ×2000
Thermostat adjustment range °C 55 ÷ 80 55 ÷ 80 55 ÷ 80 55 ÷ 80 55 ÷ 80
Output
Fornace output
Thermal load
Thermal output

7
PRK 1520 PRK 1870 PRK 2350 PRK 3000 PRK 3500
kW
kcal/h x 1000
1.180 ÷ 1.520
1.014,8 ÷ 1.307,2
1.480 ÷ 1.870
1.278,8 ÷ 1.608,2
1.830 ÷ 2.350
1.573,8 ÷ 2.021
2.450 ÷ 3.000
2.107 ÷ 2.580
2.780 ÷ 3.500
2.390,8 ÷ 3.010
kW
kcal/h x 1000
1.270 ÷ 1.664
1.092,9 ÷ 1.431
1590 ÷ 2045
1.367,4 ÷ 1.758,7
1.980 ÷ 2.572
1.702,8 ÷ 2.211,9
2.642 ÷ 3.285
2.272,1 ÷ 2.825,1
3.015 ÷ 3.835
2.592,9 ÷ 3.298,1
Combustion chamber volume m³ 1,55 1,94 2,577 3,033 3,636
kW/m³
kcal/h m³
1.073,5
923.210
1.050
903.086
998
858.280
1.083
931.454
1.054,7
907.068
Exchange surface m² 33,1 41,2 49,5 57,8 71,1
kW/m²
kcal/h m²
45,9
39.492
45,4
39.034
47,5
40.828
51,9
44.637
49,2
42.335
Smoke duct number n° 61 69 79 99 128
Smoke duct diameter Ø est. 1½” 1½” 1½” 1½” 1½”
Boiler weight kg 2.610 3.220 4.010 6.030 7.240
Water content lt. 1.650 2.080 2.690 3.740 4.490
Operating pressure bar 6 6 6 6 6
Hydraulic pressure bar 9 9 9 9 9
Max. operatine temperature °C 95 95 95 95 95
Water loss of heat ∆t=15°C mbar
43 46 40 58 40
Combustion chamber pressure mbar 5,8 6 6 6,5 6,8
Minimum efficiency at 100% % 89,2 89,2 89,2 89,2 89,2
Efficiency at 100% % 91,35 91,4 91,5 91,4 91,3
Minimum effciency at 30% % 87,8 87,8 87,8 87,8 87,8
Efficiency at 30% % 92,8 92,9 92,9 92,5 93,2
Loss of heat at the chimney with working burner % 8,22 8,2 8,12 8,21 8,29
Loss of heat at the chimney with burner out % 0,17 0,20 0,18 0,2 0,16
Loss of heat at the jacket ∆t=50°C %
0,43 0,4 0,38 0,39 0,41
Burner connection (Ø) mm 320 370 370 370 370
Flue connection (Ø) mm 450 500 550 600 700
Min. chimney depression mbar 0,2 0,2 0,2 0,2 0,2
Max smoke temperature °C 197 188 193 188 195
Smoke temperature in the output range °C 147 ÷ 197 149 ÷ 188 159 ÷ 193 152 ÷ 188 155 ÷ 195
CO2a gas % 10,2 9,8 10,4 10,2 9,9
CO a gas ppm 69 55 70 77 68
NOx a gas ppm 71 52 72 74 73
Max. light oil smoke flow rate m³/h 3.928 4.828 6.276 8.016 9.358
Max. methane smoke flow rate m³/h 3.490 4.289 5.691 7.269 8.486
Light oil burning air volume (practice) m³/h 2.146 2.638 3.311 4.229 4.937
Methane burning air volume (practice) m³/h 1.989 2.445 2.949 3.766 4.397
Combustion chamber dimensions (DiameterxLenght) mm 880 ×2.550 944 ×2.760 1.020 ×2.780 1.211 ×2.720 1.211 ×3.000
Thermostat adjustment range °C 55 ÷ 80 55 ÷ 80 55 ÷ 80 55 ÷ 80 55 ÷ 80
Output
Fornace output
Thermal load
Thermal output

8
2.4 DIMENSIONS OF PRK BOILERS
1 Switchboard AB Burner connection
2 Sight glass AV Expansion safety connection
4 Cleaning door smoke chamber AC Flue connection
AM Flow connection AS Discharge
AR Return connection
Note: The clearance "M" is lower than "H" in the models PRK 1050 up to PRK 2350. The connection "AV" is
between "AR" and "AM".
Mod. 350 420 470 520 600 700 830 940 1050 1200 1520 1870 2350 3000 3500
Amm 920 920 1100 1100 1100 1215 1215 1410 1410 1410 1480 1590 1690 1910 1910
Bmm 1105 1105 1245 1245 1245 1330 1300 1450 1450 1450 1580 1700 1850 2065 2065
Cmm 1765 1900 1805 1805 2170 2125 2325 2450 2450 2850 3320 3600 3600 3680 4140
Dmm 1415 1555 1410 1410 1780 1660 1910 1960 1960 2360 2765 3005 3005 2965 3280
Gmm 640 640 720 720 720 760 760 850 850 850 900 900 900 920 900
Hmm 540 680 450 450 800 620 870 1125 1125 1450 1830 2030 1230 1200 1320
Mmm 835 975 770 770 1120 970 1220 575 575 750 950 1015 1722 1780 1900
Nmm 500 500 650 650 650 700 700 750 750 750 830 900 970 1095 1095
Rmm 790 790 850 850 850 920 920 790 790 790 800 900 970 1095 1095
Smm 850 850 1030 1030 1030 1125 1125 1320 1320 1320 1400 1500 1600 1830 1830
Tmm 1375 1515 1365 1365 1715 1615 1865 1920 1920 2320 2720 2960 2960 2920 3230
AR - AM
Ø DN 80 80 100 100 100 125 125 125 125 125 150 150 200 200 250
AV
Ø DN 2” 2” 2½” 2½” 2½” 2½” 2 ½” 3” 3” 3” 100 100 100 125 125
AS
Ø DN 1” 1” 1¼” 1¼” 1¼” 1¼” 1 ¼” 1½” 1½” 1½” 1½” 1½” 1½” 2” 2”
AC
Ø mm 250 250 300 300 300 350 350 400 400 400 450 500 550 650 650
AB
Ø mm 210 210 240 240 240 240 240 305 305 305 320 345 345 370 370

9
3. SWITCHBOARD
3.1 SWITCHBOARD
1. General switch with green light 9. Manual reset safety thermostat
2. Burner switch 10. Boiler thermometer
3. System pump switch 15. System pump (inside)
5. Running light system pump 16. Anti-inertia thermostat (inside)
8. Boiler adjustment thermostat
3.2 WIRING DIAGRAM
IG General switch TIT Anti-inertia thermostat
IP System pump switch (PI) PI System pump
IB Burner switch S Light in IG included
TS Safety thermostat S2 Running light PI
TR Boiler adjustment thermostat S3 Burner block-out light
TM Min. temperature thermostat B4 Hour meter
TA Room thermostat

10
3.3 TERMINAL BOX CONNECTIONS
3.4 WATER STORAGE CYLINDER CONNECTIONS
TP Priority thermostat PI System pump
TA Room thermostat PB
Water
cylinder pump
T.MAX Anti-inertia thermostat (outside)
Following these connections you will have this running:
− the pump runs only if the boiler exceeds the allowed
minimal temperature,
− water cylinder priority, by means of the thermostat TP -
fast reaching of the set point temperature,
− reducing the possible thermal inertia through the water
storage cylinder.
Attention:
TP and T.MAX thermostats are not included in the boiler. They have to be delivered and connected by the
installer.
3.5 RUNNING
Bring all the switches to the position "1", adjust the set point boiler temperature by means of the TR thermostat
(position number 8 on the switchboard). The PI system pumps starts running when the boiler reaches the
minimal temperature. The red light on the switchboard number 5 position will shine.
The possible room thermostat is to be connected to the terminals 15-17 after having taken away the bridge. The
room thermostat acts only on the system pump.
In case of thermal inertia formation the thermostat makes the system pump operate if the boiler temperature
reaches 90°C.
The switchboard of MK and PRK boilers satisfies the demands required by present regulations:
− 73/23/CEE Low voltage;
− 89/336/CEE Electromagnetic Compatibility.

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4. BURNERS
The burner is important and its choice depends on its accordance with the output and counter pressure values
that are described in the two tables at pages 2 and 3. As far as the burner connection is concerned, follow these
instructions.
L = minimal length of the burner head
Boiler model L
MK 55-65-80 150
MK 90-100-120 170
MK 140-170 170
MK 220-280 200
PRK 320-400 220
PRK 500-600-740-830 260
PRK 1050-1200 300
PRK 1450 350
PRK 1850-2350 400
PRK 3000-3500 450
Blast tubes are to be wrapped with a glass fibre or mineral wool insulation, in order to avoid burner plate
overheating and furnace heat losses.
Important:
Even if the burner is delivered by ARCA, it has not the same warranty as the boiler. Its warranty depends on the
conditions established by its producer. Authorised personnel must effectuate the installation, the first ignition
and the burner maintenance.

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4.1 MINIMAL VALUE OF THE BURNER OUTPUT AT FIRST STAGE
If you have a two-stage burner, the first flame has to be set according to the values shown in the following table
in order to prevent boiler corrosion. The smoke temperature is not to be lower than 120°C.
MODEL MIN. BURNER OUTPUT AT
FIRST STAGE kcal/h (kW)
MK 100 54'000 (63)
MK 120 64'000 (74)
MK 140 72'000 (83)
MK 170 88'000 (102)
MK 220 106'000 (123)
MK 280 132'000 (153)
PRK 320 160'000 (186)
PRK 400 225'000 (262)
PRK 500 275'000 (320)
PRK 600 335'000 (390)
PRK 740 412'000 (480)
PRK 830 464'000 (540)
PRK 1050 568'000 (660)
PRK 1200 653'000 (760)
PRK 1450 790'000 (920)
PRK 1850 1'005'000 (1170)
PRK 2350 1'280'000 (1490)
PRK 3000 1'548'000 (1800)
PRK 3500 1’800'000 (2100)
5. INSTALLATION
5.1 HYDRAULIC DIAGRAM
Legend:
C Boiler PA Anti-condensation pump
P Air bleeding PI System pump
S Safety valve VE Expansion vessel
VM Mixing valve GR Water loading group
VR Non-return valve A Hydraulic alimentation
M System flow D Litre meter
R System return

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5.2 JACKET MOUNTING
MK 55÷170
− Place the generator Ref.1 in the boiler room and
make all hydraulic and smoke discharge duct
connections.
− Wrap the boiler body with glass fibre insulation
Ref.2, by cutting it near the flow duct and fix it
by means of Ref.3 holding strips.
− The insulation front panel Ref.4 is fixed to the
door.
− Mount side panels Ref.5 and Ref.6 taking care
of inserting them correctly into Ref.7 and Ref.8,
the front and back duct plates, and the bended
part in the boiler base.
− Fix the panel Ref.11, just over the door, into the
bayonet-joints of the side panels Ref.5 and
Ref.6.
− Insert panels Ref.9 and Ref.10 into the back
part of side panels Ref.5 and Ref.6, place them
by means of a light pressure.
− Place the upper cover Ref.13 between side
panels Ref.5 and Ref.6, after having screwed
them into the switchboard Ref.12 and having
unrolled thermostat cords. Connect them.
MK 220÷280
Follow the above-described instructions for all
models up to MK 170, place the back panel Ref.14
as described in the picture.

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PRK 320÷740
− Place the generator Ref.1 in the boiler room and
make all hydraulic and smoke discharge duct
connections.
− Wrap the boiler body with glass fibre insulation
Ref.2, by cutting it near the flow duct and fix it by
means of Ref.3 holding strips. The greater is the
boiler output, the higher is the quantity of the
insulation material.
− The front panel Ref.4 is delivered already fixed to
the door.
− Mount side panels Ref.5 and Ref.6 taking care of
inserting them correctly into Ref.7 and Ref.8, the
front and back duct plates, and the bended part in
the boiler base.
− Insert panels Ref.7 and Ref.8 into Ref.5 and Ref.6
bayonet-joints.
− Insert panels Ref.9 into panels Ref.5 and Ref.6,
toward the boiler front side after having screwed
the switchboard Ref.10 and unrolled cords.
− Insert the half-covers Ref.11 and Ref.12 between
side panels Ref.5 and Ref.6 into side panel Ref.8
and Ref.9.
PRK 830÷3500
− Place the generator Ref.1 in the boiler room
and make all hydraulic and smoke discharge
duct connections.
− Wrap the boiler body with glass fibre insulation
Ref.2, by cutting it near the flow duct and fix it
by means of Ref.3 holding strips. The greater
is the boiler output, the higher is the quantity
of the insulation material.
− The front panel Ref.4 is delivered already fixed
to the door.
− Mount side panels Ref.5, 6 and 8 to the proper
upper cover and boiler base. In boilers with
higher output every side panel consists of 3
panels.
− Insert panels Ref.9 and Ref.10 into side
panels Ref.7 and Ref.5 and Ref.8 and Ref.6
fixing them into their proper bayonet-joints.
− Place the cover Ref.11 by insert it into the side
panels Ref.7 and Ref.5, toward the boiler front
side, after having screwed the switchboard
and unrolled the thermostat cords.
− Place half-covers Ref.13 and 14 among side
panels Ref.5, 6, 7 and 8 by placing them on
the side panel Ref.10 and 11 inward parts.

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5.3 ANTICONDENSATION PUMP
In order to avoid system damages caused by unburnt gas condensation, it is necessary to insert a circulating
pump between the flow and the return.
The anti-condensation output can be calculated as follows:
− 1° method = boiler / 45 = l/h
− 2° method = water flow / 3 = l/h
The pump prevalence value will be the one indicated in the table about boiler specifications and, in particular,
about the water heat loss.
5.4 FLUE
The flue has an important role for the installation of a high efficiency boiler.
Low smoke temperatures and methane combustions require condensation proof flues. These flues have to be
highly insulated and corrosions proof.
On the market there are different companies which produce the kind of flues described and deliver flue
dimensions in accordance with local regulations.
6. USAGE
6.1 FIRST IGNITION CONTROL
At the first boiler and system ignition follow these instructions:
− control the normal thermostat running;
− control the correct placing of spiral coils up to the smoke combustion chamber;
− control the boiler and flue connection tightness; take away all the possible openings by using glass fibre cord
resistant to high temperatures.
− Control the front door tightness; in particular control there is no smoke coming out of the boiler and burner
connection.
− Control the flue draught when the system is operating, control the flue depression.
− Control the expansion vessel water level. The water level must respect foreseen levels. If steady water
adding are required, search for their cause, i.e. water losses, insufficient expansion vessel volume etc. A
steady water change can result in an easier boiler corrosion and calcareous deposit formation.
Similarly, control the closed expansion vessel efficiency. Control set values of safety valves and the automatic
alimentation group. Control the system is full of water and completely without air.
At first ignition verify:
− pressure damper and safety valve set values;
− the turning sense of the water cylinder circulating pump;
− set values of the engine safety device as a protection of the water cylinder circulating pump.
6.2 RUNNING DATA
If the burner adjustment is good and using 3-5°E max. viscosity heavy oil at 50°C you will have the following
combustion data:
− CO212-14%,
− smoke emissions have not to exceed the level 4 according to Bacharach' s scale,
− smoke temperature at 200-220°C.
Using 1,4°E max. viscosity light oil at 20°C you will have the following data:
− CO211-13%,
− smoke emissions have not to exceed the level 0-1 according to Bacharach' scale,
− smoke temperature at 180-200°C.
Using methane:
− C
O
28-10,5%,
− C
O
< 0,1%,
− smoke temperature at 160-200°C.
These values are possible if the boiler is clean and the water temperature at 80-90°C.

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6.3 REDUCED OUTPUT RUNNING
The reduced output running of MK and PRK boilers can be successfully used during autumn and spring and
when the system runs partially.
To obtain it extract all the metal spiral coils from ducts.
This operation results in an increasing in smoke temperature so that it is necessary to reduce the burner
capacity of about 30%.
In this way you have an output decreasing without having an efficiency decreasing.
Always control the smoke temperature is not lower than 180°C and not higher than 220°C. The reduced output
running is profitable also during summer in case of combined boilers.
It is better to tailor the fuel capacity to the system thermal need. A high number of burner ignitions
damage the boiler.
6.4 BOILER WATER TEMPERATURE
The heating system water temperature is to be adjusted according to the room thermal need by acting on:
a) the burner
b) the boiler thermostat
c) the mixing valve
The latter represents the better way to do it because it allows a high boiler temperature even when the heating
system water temperature is low. In this way you have a good protection against corrosion and the boiler will
run longer.
The return water has never to be lower than:
− 45°C using gas, light or heavy oil with a sulphur percentage lower than 1%,
− 50°C using heavy oil with a sulphur percentage higher than 1%.
Under these limits, smokes can reach their condensation point and build up sulphur acid compounds on the
smoke duct surface. In this way the duct bundle can be damaged.
6.5 SYSTEM IGNITION
The possible opening of cold secondary circuits during the boiler running has to be carried out step by step.
It is advisable to control the circulating pump by means of a thermostat installed in the boiler switchboard (see
page 10).
6.6 BOILER THERMOSTAT SET VALUES
Operating thermostat set values must be established according to heating system specifications.
In case there is a mixing valve and a circulating pump, the operating thermostat can be set at 85-90°C to avoid
return temperatures lower than the values shown in the paragraph 6.4.